1. Field of the Invention
This invention relates to a radiation image recording and read-out apparatus using a stimulable phosphor sheet. This invention particularly relates to a radiation image recording and read-out apparatus comprising a rotatable image recording section and an image read-out section which are formed integrally with each other.
2. Description of the Prior Art
When certain kinds of phosphors are exposed to a radiation such as X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays or ultraviolet rays, they store a part of the energy of the radiation. Then, when the phosphor which has been exposed to the radiation is exposed to stimulating rays such as visible light, light is emitted by the phosphor in proportion to the stored energy of the radiation. A phosphor exhibiting such properties is referred to as a stimulable phosphor.
As disclosed in U.S. Pat. Nos. 4,258,264, 4,276,473, 4,315,318 and 4,387,428, and Japanese Unexamined Patent Publication No. 56(1981)-11395, it has been proposed to use a stimulable phosphor in a radiation image recording and reproducing system. Specifically, a sheet comprising the stimulable phosphor is first exposed to a radiation passing through an object to have a radiation image stored therein, and is then scanned with stimulating rays which cause it to emit light in proportion to the radiation energy stored. The light emitted by the stimulable phosphor sheet when the sheet is exposed to the stimulating rays is photoelectrically detected and converted to an electric image signal, which is processed as desired to reproduce a visible image having an improved quality, particularly a high diagnostic efficiency and accuracy. The finally obtained visible image may be reproduced on a recording material such as a photographic film or on a display device such as a cathode ray tube (CRT).
As the image recording apparatus for obtaining a radiation image of an object, there has heretofore been known an apparatus wherein a radiation source and an image recording position provided with a recording medium such as an X-ray film are positioned to face each other via the object and are integrally rotated together with the object or around the object. For example, in the case where the stomach of the human body is examined, the object (i.e. the human body) injected with a contrast medium is placed on a rotatable bed, and image recording is conducted by rotating the bed and inclining it at a predetermined angle. In the Magen image recording apparatus of this type, the radiation source and the image recording position where the recording medium is exposed to a radiation emitted by the radiation source via the object are constituted so that they are integrally rotatable together with the rotatable bed. Also in an image recording apparatus for mammography, the radiation source and the image recording position where the recording medium is positioned are constituted so that they are integrally rotatable around the mamma.
When the aforesaid stimulable phosphor sheet is used as the recording medium in the aforesaid rotatable image recording apparatus, it becomes necessary to use an image read-out apparatus for detecting the radiation image recorded on the stimulable phosphor sheet at the image recording apparatus. In this case, it is disadvantageous for the image recording apparatus and the image read-out apparatus to be formed separately, and they should be formed integrally with each other as an image recording section and an image read-out section of a single apparatus so that recording of the radiation image on the stimulable phosphor sheet and read-out of the radiation image from the stimulable phosphor sheet are carried out continuously.
When the image recording section and the image read-out section are formed integrally in a single apparatus, the image read-out section should not be rotated together with the rotatable image recording section since this makes the mechanism of the whole apparatus complicated and the apparatus large. Further, when the image read-out section is rotated together with the image recording section, a very real problem arises because of vibration caused by rotation at the image read-out section. For example, as the image read-out section rotates, vibration is transmitted to the image read-out optical system, and it is not always possible to conduct scanning of stimulating rays correctly. Also, the load on a motor for conveying the stimulable phosphor sheet at the image read-out step is caused to fluctuate, and it is not always possible to convey the stimulable phosphor sheet accurately and to read out the radiation image accurately. Further, in general, it is desired for the radiation image recording apparatus to be able to record a predetermined number of images when necessary. Particularly, in Magen image recording or the like, it is required to record a predetermined number of images continuously at arbitrary timing. Therefore, also when the image recording section and the image read-out section are formed integrally, it is desirable that image recording be conducted continuously at arbitrary timing independent of image read-out.